Air Conditioning Terms

Air Conditioning Terms

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Air Conditioner

An appliance, system, or mechanism designed to dehumidify and extract heat from an area. Usually, this term is reserved for smaller self-contained units such as a residential system.

Air Handler

A central unit consisting of a blower, heating and cooling elements, filter racks or chamber, dampers, humidifier, and other central equipment in direct contact with the airflow. This does not include the ductwork through the building. Abbreviated AH or AHU.

British Thermal Unit (BTU)

Any of several units of energy (heat) in the HVAC industry, each slightly more than 1 kJ. One BTU is the energy required to raise one pound of water one degree Fahrenheit, but the many different types of BTU are based on different interpretations of this “definition”. In the United States, the power of HVAC systems (the rate of cooling and dehumidifying or heating) is sometimes expressed in BTU/hour instead of watts. Abbreviated BTU or Btu.


Equipment that performs heat transfer to air when mounted inside an air handling unit or ductwork. It is heated or cooled by electrical means or by circulating liquid or steam within it.


A component in the basic refrigeration cycle. Contains a compressor that adds heat to refrigerant, then with the assistance of a fan condenses that compressed gas to a liquid.


A digital or mechanical device that controls the operation of a system. It may simply turn a device on and off, or it may more subtly modulate the set point of components. Most controllers are automatic but have user input such as temperature set points.


Specialized housing for the airflow. It can be sheet metal or flexible plastic ductwork. The majority of ductwork is insulted, but not always.


A dehumidifier is the equipment that extracts and removes humidity from the air. It works by cooling air to the point where water turns to liquid from vapor form and then the liquid is removed.


Component in the basic refrigeration cycle that absorbs or adds heat to the system. Evaporators can be used to absorb heat from air or from a liquid. The evaporator is the cold side of an air conditioner or heat pump.


A component of an HVAC system that adds heat to air or an intermediate fluid by burning fuel (natural gas, oil, propane, butane, or other flammable substances) in a heat exchanger.

Gas Furnace Heat Exchanger

A gas furnace heat exchanger is responsible for the transfer of heat from inside the furnace into the air outside the furnace. The duct system then transfers this exchanged air to different rooms in the building or space.


A cover of a duct opening, often rectangular, containing multiple parallel slots through which air may be delivered or withdrawn from a ventilated space. The grille directs the airflow in a particular direction and prevents the passage of large items.

Heating Coil

A heating coil is the part of the system that converts electricity to heat. Electricity is running through a specially designed wire that glows hot and the air is then blown over it producing warm air.

Heat Pump

A heat pump is very similar to a condenser; however, when there is a call for heat it reverses the refrigerant flow and produces a hot indoor coil rather than a cold. Contact us for Heat Pump Replacement  in Waxahachie  in the surrounding areas.

Split System

A split system is the combination of an outdoor unit and an indoor unit. This is the most common type of system.


The condition where liquid refrigerant is colder than the minimum temperature required to keep it from boiling would change it from a liquid to a gas phase. Subcooling is the difference between its saturation temperature and the actual liquid refrigerant temperature.


General term is used to refer to the set or a subset of components that perform a specific HVAC function within a building.


A thermostat is a system that monitors and regulates a heating or cooling system. It can be used to set the desired temperature at which it keeps the environment either heated or cooled.

Two-Stage (cooling and heating)

A two-stage air conditioner is designed to operate on high and low settings during different weather conditions and seasons. The high setting is used during extreme weather, and the low setting is used during moderate weather. This type of air conditioner produces a balanced temperature and is in use for a longer period of time.

TXV – Thermostatic Expansion Valve

A thermostatic expansion valve is a piece of equipment that meters the flow of liquid refrigerant into the evaporator while measuring the vapor refrigerant leaving the evaporator. It thereby controls the superheating at the outlet of the evaporator.

Variable Air Volume

An HVAC system that has a stable supply-air temperature, and varies the airflow rate to meet the temperature requirements. Compared to constant air volume systems, these systems conserve energy through lower fan speeds during times of lower temperature control demand. Most new commercial buildings have VAV systems. VAVs may be bypass type or pressure dependent. Pressure dependent type VAVs save energy while both types help in maintaining temperature of the zone that it feeds. Abbreviated VAV.

Zoning System

A zoning system sections a building or a space into zones, which are controlled independently of each other. This is beneficial when different areas or rooms of a building have different temperatures as well as when the desired temperatures in different rooms are different. Temperature is controlled by different thermostats.

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YP Reviews

Marsha W. On 10.26.2017

Repairman Nick came out to service AC and actually need some repair due to bad install for unit. I have received the most courteous, professional and a very fair quote on work needed to be done. He had…

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